1. Field of the Invention
The present invention relates to a copier having an optically scanning device for scanning an original and scanning a photo-sensitive substance by using a light source such as a laser or the like.
2. Description of the Related Art
As a conventional apparatus for reading and recording an image by using a laser light, an apparatus which switches an optical path of a laser light between an original side and a photo-sensitive substance side by means of a reflection mirror etc. is known as disclosed in Japanese Patent Publication No. Hei 2-58605. This apparatus performs reading and recording operations in a main scanning direction by using: a polygon mirror for deflecting the laser light at a constant angular velocity; and an f xcex8 lens for converting the angular deflecting operation into a linear scanning operation at a constant linear velocity. Further, the apparatus performs the reading operation in a sub-scanning direction by moving an original base, on which an original is placed, to a direction perpendicular to an incident direction of the light beam (i.e., perpendicular to the main scanning direction), and performs a recording operation in the sub-scanning direction by rotating the photo-sensitive substance such as a photosensitive drum.
However, a read width in the main scanning direction is fixed according to the above mentioned conventional apparatus, so that a length of an image read for each unit time is constant. Thus, in order to enlarge or shrink the image, it is necessary to once store the read image in a frame memory to thereby digitally process the stored information.
As a result, it is difficult to make a copy time shorter and implement a reduction of a cost needed for the frame memory.
It is therefore an object of the present invention to provide a copier equipped with a light source for emitting a light having a predetermined wave length, which can enlarge or shrink an original with a fast speed and a low cost.
The above object of the present invention can be achieved by a copier provided with: an original base on which an original is placed; a photo-sensitive substance on which a latent image corresponding to an image of the original is to be recorded; a light source device for emitting light; a deflecting device for deflecting the emitted light in a main scanning direction, to thereby perform a main scanning operation for each scanning line in the main scanning direction; a light collecting device for collecting the deflected light, to thereby irradiate the original and the photo-sensitive substance with the collected light respectively; a guiding device for guiding the collected light to the original and the photo-sensitive substance respectively; a light detecting device for reading the image of the original by receiving a scattered light from the irradiated original for the each scanning line at a reading cycle, and outputting image information, which indicates the image of the original; a sub-scanning direction moving device for relatively moving the collected light with respect to the original and the photo-sensitive substance respectively in a sub-scanning direction, to thereby perform a sub-scanning operation in the sub-scanning direction; a memory device for storing the outputted image information for the each scanning line; a light recording device for recording the latent image onto the photo-sensitive substance for the each scanning line at a recording cycle by reading out the stored image information from the memory device and driving the light source device to emit the light on the basis of the read out image information; and a magnification control device for relatively varying the reading cycle and the recording cycle with respect to each other.
According to the copier of the present invention, the light for reading the image of the original included in the emitted light from the light source device is deflected by the deflecting device in the main scanning direction, is collected by the light collecting device, and is guided by the guiding device, to be incident to the original placed on the original base. Then, the scattered light from the irradiated original is received by the light detecting device, so that the image of the original is read by the light detecting device, for each scanning line at the reading cycle. Then, the image information is outputted from the light detecting device and is stored into the memory device for each scanning line at the reading cycle.
On the other hand, the stored image information is read out from the memory device, and the light source device is driven to emit the light, on the basis of the read out image information, by the light recording device. The light for recording the latent image included in the emitted light from the light source device is deflected by the deflecting device in the main scanning direction, is collected by the light collecting device, and is guided by the guiding device, to be incident to the photo-sensitive substance. In this manner, the latent image is recorded by the light recording device onto the photo-sensitive substance for each scanning line at the recording cycle.
Further, by the sub-scanning direction moving device, the collected light is relatively moved with respect to the original and the photo-sensitive substance respectively in the sub-scanning direction.
Accordingly, a two dimensional scanning operation is performed for reading the image of the original, and a two dimensional scanning operation is performed for recording the latent image onto the photo-sensitive substance. Therefore, if the reading cycle and the recording cycle are equal to each other, the scan width for reading the image of the original and the scan width for recording the latent image onto the photo-sensitive substance are also equal to each other, so that a copying operation with an equivalent magnification is performed. On the other hand, if the reading cycle and the recording cycle are relatively varied with respect to each other by the magnification control device, the scan width for reading the image of the original and the scan width for recording the latent image onto the photo-sensitive substance are different from each other, so that a copying operation with an enlargement or shrinkage is performed.
Consequently, it is possible to speedily perform the copying operation with the enlargement or shrinkage, while it is possible to reduce the cost of the copier since a frame memory is not necessary for the copying operation with the enlargement or shrinkage.
In one aspect of the copier of the present invention, the magnification control device relatively varies (i) an emitting cycle of the light emitted from the light source device to the original and (ii) an emitting cycle, based on the read out image information, of the light from the light source device to the photo-sensitive substance, with respect to each other.
According to this aspect, on one hand, if the emitting cycle of the light to the original is varied by the magnification control device, the image information outputted by the light detecting device and stored into the memory device is delayed or advanced in time as compared with the case for the equivalent magnification. Therefore, the scan width for reading the image of the original and the scan width for recording the latent image onto the photo-sensitive substance are different from each other, so that the copying operation with the enlargement or shrinkage is performed. On the other hand, if the emitting cycle of the light to the photo-sensitive substance is varied by the magnification control device, the image information read out from the memory device is delayed or advanced in time as compared with the case for the equivalent magnification. Therefore, the scan width for reading the image of the original and the scan width for recording the latent image onto the photo-sensitive substance are different from each other, so that the copying operation with the enlargement or shrinkage is performed.
In another aspect of a copier of the present invention, the magnification control device relatively varies (i) a storing cycle for storing the outputted image information into the memory device and (ii) a reading out cycle for reading out the stored image information from the memory device, with respect to each other.
According to this aspect, on one hand, if the storing cycle is varied by the magnification control device, the image information stored into the memory device is delayed or advanced in time as compared with the case for the equivalent magnification. Therefore, the scan width for reading the image of the original and the scan width for recording the latent image onto the photo-sensitive substance are different from each other, so that the copying operation with the enlargement or shrinkage is performed. On the other hand, if the reading out cycle is varied by the magnification control device, the image information read out from the memory device is delayed or advanced in time as compared with the case for the equivalent magnification. Therefore, the scan width for reading the image of the original and the scan width for recording the latent image onto the photo-sensitive substance are different from each other, so that the copying operation with the enlargement or shrinkage is performed.
In this aspect, the magnification control device may interpolate the outputted image information before being stored into the memory device when the reading out cycle is relatively longer than the storing cycle, and may thin out the outputted image information before being stored into the memory when the reading out cycle is relatively shorter than the storing cycle.
Thus, on one hand, if the reading out cycle is set longer than the storing cycle, the scan width for recording the latent image onto the photo-sensitive substance is longer than the scan width for reading the image of the original, so that the copying operation with the enlargement is performed. The number of recording pixels obtainable by the outputted image information runs short for such a longer main scanning line. Therefore, by the magnification control device, the outputted image information before being stored into the memory device is interpolated, so that the number of recording pixels are compensated. On the other hand, if the reading out cycle is set shorter than the storing cycle, the scan width for recording the latent image onto the photo-sensitive substance is shorter than the scan width for reading the image of the original, so that the copying operation with the shrinkage is performed. The number of recording pixels obtainable by the outputted image information is in excess for such a shorter main scanning line. Therefore, by the magnification control device, the outputted image information before being stored into the memory device is thinned out, so that the necessary memory capacity of the memory device is not increased.
Further in this case, a reading clock on the basis of which the light detecting device reads the image of the original may be constant, and a recording clock on the basis of which the light recording device records the latent image may be constant. Thus, even if each of the reading clock and the recording clock is constant, because of the interpolating and thinning-out operations by the magnification control device, the copying operation with the magnification or shrinkage can be speedily performed without the frame memory, while preventing the recorded latent image from being rough and restraining the unnecessary of the memory capacity of the memory device.
In another aspect of the copier of the present invention, the copier is further provided with a moving speed varying device for varying a moving speed of the sub-scanning direction moving device, in association with a relative change between the reading cycle and the recording cycle.
According to this aspect, along with the relative change between the reading cycle and the recording cycle, the moving speed of the sub-scanning direction moving device is changed. At this time, the moving speed of the sub-scanning direction moving device is varied by the moving speed varying device, in association with the relative change between the reading cycle and the recording cycle, so that it is possible to perform the copying operation with the magnification or shrinkage in which the magnification or shrinkage ratio in the main scanning direction is equal to that in the sub-scanning direction.
In another aspect of the copier of the present invention, the memory device comprises: a first memory for storing the image information, which is outputted by the light detecting device; and a second memory for storing the image information, which is transferred from the first memory and is to be read out by the light recording device.
According to this aspect, at first, the image information, which is outputted by the light detecting device, is stored into the first memory. Then, the image information is transferred from the first memory to the second memory, so that the image information is read out from the second memory by the light recording device. Accordingly, since the reading operation by the light detecting device and the recording operation by the light recording device can be simultaneously performed, so that the speedy copying operation is realized.
In another aspect of the copier of the present invention, a plurality of light detecting devices each comprising the light detecting device are arranged at the vicinity of a surface of the original base and at a plurality of positions along the main scanning direction.
According to this aspect, since the image of the original is read by a plurality of light detecting devices, the reading operation is accurately performed at a high accuracy, and the enlargement or shrinkage can be also accurately performed.
In another aspect of the copier of the present invention, the magnification control device is provided with a reading clock control circuit for varying a reading clock on the basis of which the light detecting device reads the image of the original while the recording cycle is constant.
According to this aspect, the reading clock is varied by the reading clock control circuit. Thus, the reading cycle can be varied just by changing the reading clock while it is not necessary to change the recording cycle. Therefore, the copying operation with the enlargement or shrinkage can be speedily performed by use of a relatively simple construction.
In another aspect of the copier of the present invention, the magnification control device is provide with a recording clock control circuit for varying a recording clock on the basis of which the light recording device records the latent image while the reading cycle is constant.
According to this aspect, the recording clock is varied by the recording clock control circuit. Thus, the recording cycle can be varied just by changing the recording clock while it is not necessary to change the reading cycle. Therefore, the copying operation with the enlargement or shrinkage can be speedily performed by use of a relatively simple construction.
In another aspect of the copier of the present invention, the light source device is provided with: a first light source for emitting the light to read the image of the original; a second light source for emitting the light to record the latent image; and a light synthesizing device for synthesizing the light emitted by the first light source and the light emitted by the second light source. And that, the guiding device is provided with a light separating device for separating the synthesized light into the light to the original and the light to the photo-sensitive substance.
According to this aspect, the light to read the image of the original is emitted by the first light source while the light to record the latent image is emitted by the second light source. Then, the light emitted by the first light source and the light emitted by the second light source are synthesized to each other by the light synthesizing device. Then, after the light is deflected by the deflecting device and is collected by the collecting device, the synthesized light is separated into the light to the original and the light to the photo-sensitive substance, by the light separating device. Such a separation as well as a synthesis of the light may be performed on the basis of a difference in the wavelength between the lights emitted by the first and second light sources. Thus, the deflecting device such as a polygon mirror or the like and the collecting device such as a condenser lens or the like can be commonly used for the light to read the image of the original and the light to record the latent image. Therefore, the copying operation with the enlargement or shrinkage can be speedily and accurately performed.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.